<!DOCTYPE html>
<html lang="cn">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>for循环嵌套</title>
</head>

<body>

</body>

</html>
<script>
    let num1 = prompt("请输入一个数");
    let num2 = prompt("请输入第二个数");
    for (i = 1; i <= num1; i++) {
        for (j = 1; j <= num2; j++) {
            document.write("A");
        }
        document.write("<br>");
    }
</script>